淮河支流西淝河污染物质负荷输出特征

Characterization of Pollutants Outflow in Xifei River of Huaihe River’s Tributary

淮河污染物质主要来源于各小流域支流,因此研究支流污染物质输出特征对淮河的污染物质减排和水质管理具有十分重要的科学意义。选取淮河支流西淝河为研究对象,于2018年1—12月期间对流域出水口断面水量、水质[高锰酸盐指数(permanganate index,COD_(Mn))、总氮(total nitrogen,TN)和总磷(total phosphorus,TP)等]进行高频次的同步监测,分析污染物质的负荷特征。监测和数据分析分雨期和非雨期进行,其中雨期为3—9月,非雨期1、2、10、11、12月,汛期主要为5—9月。研究结果表明,西淝河出流COD_(Mn)浓度变化范围是2.8~10.2 mg/L,年均值5.4 mg/L,TN浓度变化范围是0.82~3.80 mg/L,年均值2.04 mg/L,TP浓度变化范围是0.01~0.34 mg/L,年均值为0.11 mg/L。西淝河流域污染物质输出具有明显的季节性变化,COD_(Mn)、TP浓度和负荷随时间变化趋势与流量一致,雨期浓度均高于非雨期浓度,在汛期达到最大。TN浓度、负荷随时间变化趋势与COD_(Mn)、TP不同,非雨期浓度高于雨期浓度。单位面积上COD_(Mn)年出流负荷量为22.9 kg/hm^(2),TN年负荷量为8.7 kg/hm^(2),TP年负荷量为0.46 kg/hm^(2),COD_(Mn)和TP、TN负荷量均与流量、浓度成极显著正相关,负荷输出受降雨径流影响较大。

The pollution of Huaihe River is mainly contributed from its small tributaries.Therefore,characterization of the pollutants outflow from these tributaries is important for pollution reduction and water quality management in Huaihe River.One of typical tributaries,Xifeihe River of Huaihe River,was selected to monitor its flow rate and water quality,mainly including permanganate index(COD_(Mn)),total nitrogen(TN)and total phosphorus(TP),from January to December 2018 with high-frequency.Then the pollutants loads were calculated in terms of flow rate and concentrations of pollutants.The data analysis was classified into rainy and dry season.The rainy seasons are from March to September,the dry seasons are January,February,October,November,and December,and the flooding seasons are from May to September.The concentration of COD_(Mn) in the outflow of Xifei River ranged from 2.8 to 10.2 mg/L with 5.4 mg/L in average.The concentration of TN ranged from 0.82 to 3.80 mg/L with 2.04 mg/L in average.And the concentration of TP ranged from 0.01 to 0.34 mg/L with 0.11 mg/L in average.The outflow of pollutants of Xifei River presented seasonal changes,with the output of COD_(Mn) and TP consistent with the flow change.The concentration and load of COD_(Mn) and TP in the rainy season are higher than those in the dry season,reaching peaks occurred in the flood season.Different from COD_(Mn) and TP,the concentration of TN in dry season are higher than that in rainy season.The COD_(Mn) load from the outflow of Xifeihe River is 22.9 kg COD_(Mn)/hm^(2)·a,the TN load is 8.7 kg N/hm^(2)·a,and the TP load is 0.46 kg P/hm^(2)·a.The load of COD_(Mn),TP,and TN show significantly correlation with flow rate and concentration,which are greatly affected by rainfall runoff.